This invention relates to a safety device for protecting a passenger of a motor vehicle from injury in a collision, which has a gas cushion able to be inflated by gas, i.e. an airbag, a housing connected to the gas cushion and open on one side, a gas generator arranged in the housing for generating gas under pressure for filling the gas cushion and at least one escape opening for the gas under pressure to escape, particularly when the passenger pitches into the gas cushion.
Safety devices of this type, also called "airbag systems" function so that, if acceleration or deceleration forces, the absolute value of which exceed a predetermined magnitude, affect the motor vehicle, a gas generator accommodated in a housing in the automobile open on one side and otherwise closed is ignited and generates gas under pressure. The ignited gas generator generates gas under pressure, by means of which a gas cushion connected to the housing is filled (i.e. inflated). The gas cushion consists of a sheet formed into a bag or sack connected in a gas tight manner to the housing wall and sealing the housing towards the open side, said sheet consisting of a gas tight material such as plastic or tightly woven fabric and in which are formed escape openings such as apertures. Alternatively (filter) loosely woven fabric in which the interstices between the threads of the fabrics act as escape openings is also used as a material for the gas cushion. When the passenger to be protected pitches or impact into or impacts on the gas cushion filled with gas under pressure, additional pressure is applied to the gas contained therein, and therefore the gas is forced out of the gas cushion by way of the escape openings. The escape openings here have a throttling effect, by means of which the body or the passenger under impact is made to brake so much that critical accelerating values no longer affect him. The rate at which the gas generator generates the gas under pressure (volume of gas generated per time unit) is dependent on the temperature. With the gas compositions usually employed today in gas generators less gas is generated per unit time at the lower limit of the operating temperature to be considered from -35.degree. C. to +85.degree. C., than with the upper temperature limit. This has the result that the gas cushion is filled in a relatively taut manner at high (external) temperatures and moreover, the catching characteristic for the passenger to the protected is therefore different to that at low temperatures where the gas cushion is filled less markedly.